A typical loading dock of a building includes an exterior doorway with an elevated platform for loading and unloading vehicles, such as trucks and trailers. When cargo is being transferred between the vehicle and the platform, it is generally safe practice to restrain the vehicle by some means to prevent the vehicle from accidentally departing the dock prematurely.
Perhaps the simplest vehicle restraint is a portable wheel chock that is manually wedged in front of a vehicle's wheel to obstruct the vehicle's forward movement. Examples of portable wheel chocks are disclosed in U.S. Pat. Nos. 6,390,245; 7,000,740; 7,040,461 and 7,226,265.
Some example vehicle restraints are permanently mounted to the dock and have a hook that engages the front edge of a truck or trailer's rear impact guard (also known as an ICC bar). Examples of such vehicle restraints are disclosed in U.S. Pat. Nos. 5,882,167; 6,116,839; 6,190,109 and 7,841,823.
Other vehicle restraints, such as those that are sometimes referred to as “wheel restraints,” are mounted to the loading dock's driveway and have an arm or wheel-blocking barrier that moves in front of a rear wheel of the vehicle to create an obstruction that inhibits the vehicle from departing from the dock prematurely. Examples of such wheel restraints are disclosed in U.S. Pat. Nos. 5,762,459; 5,582,498; 6,092,970; 6,676,360; 8,006,811 and 8,307,956 and in US patent publications 2011/0162916 and 2009/0194376.